1. Field of the Invention
The present invention relates to a miter saw having a laser, or other light source, alignment system that uses a beam of light for positioning a saw blade.
2. Background Art
Miter saws are used to cut wood and other materials at precise angles. For example, miter saws are used to cut crown moldings, cove moldings, and other trim pieces and structural members at precise angles. Miter saws generally have a circular blade that is rotated at a high rate of speed to cut workpieces. The blade is guarded by a retractable blade guard that covers the saw blade but is retracted as the blade is brought into contact with a workpiece. The workpiece is generally retained on a supporting table that is adjustable and, in conjunction with a fence, is used to position the workpiece for cutting by the saw blade.
Before cutting, workpieces are generally marked according to precise measurements to assure accuracy. A common problem with miter saws is that it takes a great deal of skill to consistently align the workpiece with the saw blade so that the saw blade cuts at the desired location and at the desired angle. With prior miter saws, it has not been possible to know if the saw alignment is proper until the saw begins to cut the material. If the workpiece is not set up at the correct location with the correct angular orientation, the workpiece may be ruined if it is not properly aligned when the saw blade contacts the workpiece.
A laser arbor for a rotary saw has been proposed in U.S. Pat. No. 5,862,727 to Kelly. The Kelly patent discloses the use of a semiconductor laser arbor for a rotary saw that is actuated by a centrifugal switch and directs a line of laser light on a workpiece. The Kelly patent does not disclose any shielding to prevent the laser from being directed into an operators eyes. Similarly, U.S. Pat. No. 6,035,757 to Caluori et al. discloses a similar semiconductor laser light beam alignment device for a rotary saw having a focusing lens that causes the light beam to be directed to the blade cut line. The Caluori patent likewise fails to disclose any shielding that prevents the laser from shining into an operator""s eyes. Both patents also fail to disclose an effective approach to preclude inadvertent operation of the laser when the arbor is disassembled. Furthermore, both patents fail to disclose a system for precisely aligning the laser with the point at which the blade cuts into the workpiece.
An example of a blade guard for a power saw is disclosed in U.S. Pat. No. 5,199,343 to O""Banion. The O""Banion patent discloses a louvered blade guard that an operator can see through while cutting a workpiece. The blade guard has tapered louvers that provide a line-of-sight through a portion of the guard while impeding ejection of cutting debris through the louvers. The O""Banion patent does not disclose or suggest a laser arbor for a rotary saw or any reason to combine the louvered blade guard disclosed with a laser alignment device.
These problems are addressed by the saw having a laser alignment system that includes a laser arbor that rotates with the saw blade on the spindle.
According to one aspect of the present invention, a miter saw (or other rotary saw) is provided that includes a motor with a spindle to which a blade is secured and rotated by the motor to cut a workpiece that is disposed on a saw base. The motor is part of a saw head assembly that is pivotally supported on the base by an arm. A laser or other directed light source (hereinafter referred to as xe2x80x9claserxe2x80x9d or xe2x80x9clight sourcexe2x80x9d) is mounted to the spindle and rotated by the motor along with the blade. The light source emits a narrow beam of light adjacent to the blade that is used to check the alignment of the blade with the workpiece. A movable guard pivots to cover at least a portion of the blade that is not engaging the workpiece. The guard has an opaque portion that blocks the beam of light to prevent the beam of light from being directed toward an operator of the saw.
According to another aspect of the invention, the miter saw described above may include a movable guard that is provided with a transparent area through which a narrow beam of light may pass to project a pattern of light. The light transparent area may be one or more transparent areas in the opaque portion of the guard, or the guard may be formed of a transparent material having one or more portions thereof that are covered by a mask. The transparent area may be formed as a single gap, or a pattern of slits, or gaps, in the mask and, if desired, in the guard. A solid or interrupted (dotted) line is thus formed on the workpiece.
According to another aspect of the invention, the narrow beam of light may be permitted to project beyond one end of the movable guard to form a solid line on the workpiece just prior to and while the blade engages the workpiece so that the operator can see the line of cut for the saw.
According to another aspect of the invention, the miter saw may include a saw base having a fence against which the workpiece may be pressed to locate one side of the workpiece. The saw base has a pivoting portion that pivots relative to the fence and may be locked in a selected angular orientation for making a miter cut in a workpiece.
According to another aspect of the invention, the movable guard cooperates with a fixed guard portion to substantially enclose the blade and block the beam of light except for an area encompassing the workpiece.
According to yet another aspect of the invention, the miter saw includes an arbor having an arbor base with a first mounting surface. A light source has a housing including a second mounting surface. The first and second mounting surfaces are secured together in a range of angular orientations for precisely aligning the light source. The mounting surfaces may be arcuate surfaces to facilitate alignment. The first and second surfaces may be secured together by a set screw or by a bonding agent. When the light source is rotated by the motor in conjunction with the blade, it emits a narrow beam of light adjacent the blade for providing a visual indication of the alignment of the blade with the workpiece.
The invention may also be characterized as a miter saw including a light source that is battery powered. The light source is mounted to an arbor having and arbor base and a cover wherein the cover is removable from the base and when removed from the base carries with it at least battery. By removing at least one battery as the cover is removed, the light source is prevented from operating when the cover is removed from the arbor base. The arbor base may include spring contacts for establishing electrical contact with the batteries that are carried by the cover when the cover is removed from the arbor base.